This invention relates to an improved steering assembly, especially but not exclusively, for a road vehicle such as a passenger car.
In a steering assembly for a vehicle a steering wheel is connected through a steering shaft to one or more road wheels. Turning the wheel allows the driver to turn the roadwheels which in turn steers the vehicle.
The position of the steering shaft, which is typically supported relative to a fixed part of the vehicle by a steering column shroud, is important as it determines the position of the wheel relative to the driver. To permit the driver to achieve a comfortable driving position the steering column may adjust for rake and or reach of the wheel. A clamp mechanism may be provided which can be released to allow the wheel to be adjusted and locked to fix the wheel in position during normal use. However, in the event of an accident involving a rapid deceleration of the vehicle it is desirable for the steering assembly to collapse longitudinally allowing the steering wheel to move towards the front of the vehicle under the weight of the driver.
The collapse of a steering assembly has in the past been achieved in many ways. In one arrangement the steering shaft is manufactured as a single component with weakenings along its length permitting it to collapse axially by a controlled deformation as a force is applied to the steering wheel. In an alternative, it is known to provide a two-part steering shaft in which one part slides axially over the other as a force is applied to the steering wheel.